1. Field of the Invention
The present invention relates to an improvement in an adapter case assembly used in a drive mechanism of a four-wheel drive vehicle, and more particularly to the construction of the adapter case assembly for preventing oil level from lowering in a transmission, caused by movement of oil from transmission to the adapter case assembly.
2. Description of the Prior Art
Most four-wheel drive vehicles are provided in its drive mechanism with an adapter case assembly for transmitting power or driving force from an engine to four road wheels. The adapter case assembly is interposed between a transmission and a transfer case thereby to transmit the driving force to the transfer case. However, when the vehicle inclines rearwardly for example during ascending a steep slope, oil within the transmission unavoidably flows out from the transmission and moves into the adapter case assembly, so that the oil level of the transmission considerably lowers. As a result, for example in case of using an automatic transmission, the oil level of the transmission will lower below an oil suction opening to generate no oil pressure for oil clutches in the transmission thereby interrupting transmission of the driving force.